3.09 Corynebacterium Diptheriae

Microbiology review for the USMLE Step 1 Exam

• Corynebacterium diphtheriae is an aerobic gram positive rod that causes diphtheria, commonly spreads through respiratory droplets
• C. diphtheriae produces an exotoxin called diphtheria toxin which can cause systemic effects by inactivating elongation factor (EF-2) via ADP-ribosylation and shutting down protein synthesis
• Diphtheria causes fever, sore throat, croup-like cough, pseudomembranous pharyngitis, severe cervical lymphadenopathy, myocarditis and cardiac arrhythmias
• Cutaneous diphtheria involves ulcerative lesions or cellulitis on the skin that can occur independently of respiratory diphtheria
• Vaccine available and there are not many cases of it in the US, tends to have an outsized effect on developing countries
• Risk factors for C. diphtheriae infection include IV drug use, homelessness, and crowded living conditions
• Treatment involves diphtheria antitoxin and penicillin or erythromycin